U.S. patent number 11,320,568 [Application Number 16/401,703] was granted by the patent office on 2022-05-03 for curved surface films and methods of manufacturing the same.
This patent grant is currently assigned to Corning Incorporated. The grantee listed for this patent is Corning Incorporated. Invention is credited to Ming-Huang Huang, Chang-gyu Kim, Hoon Kim, Soo Ho Park, Jue Wang.
United States Patent |
11,320,568 |
Huang , et al. |
May 3, 2022 |
Curved surface films and methods of manufacturing the same
Abstract
An optical element including an optically transparent lens which
defines a curved surface having a steepness given by an R/# of from
about 0.5 to about 1.0. A film is positioned on the curved surface.
The film includes an index layer. A composite layer is positioned
on the curved surface having a refractive index greater than the
index layer. The composite layer includes HfO.sub.2 and
Al.sub.2O.sub.3. The composite layer has a mole fraction X of
HfO.sub.2, wherein X is from about 0.05 to about 0.95 and a mole
fraction of Al.sub.2O.sub.3 in the composite layer is 1-X.
Inventors: |
Huang; Ming-Huang (Ithaca,
NY), Kim; Chang-gyu (Cheongju-si, KR), Kim;
Hoon (Horseheads, NY), Park; Soo Ho (Cheonan-si,
KR), Wang; Jue (Pittsford, NY) |
Applicant: |
Name |
City |
State |
Country |
Type |
Corning Incorporated |
Corning |
NY |
US |
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Assignee: |
Corning Incorporated (Corning,
NY)
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Family
ID: |
66625431 |
Appl.
No.: |
16/401,703 |
Filed: |
May 2, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190346590 A1 |
Nov 14, 2019 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62670187 |
May 11, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C
16/403 (20130101); C23C 16/45553 (20130101); G02B
5/283 (20130101); C23C 16/45529 (20130101); G02B
1/02 (20130101); G02B 1/115 (20130101); G02B
3/00 (20130101); G02B 2003/0093 (20130101) |
Current International
Class: |
G02B
1/02 (20060101); G02B 3/00 (20060101); C23C
16/455 (20060101); C23C 16/40 (20060101) |
Field of
Search: |
;359/642,586,589,584,359
;428/215,336,328,354 ;427/162,167,164 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102703880 |
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Oct 2012 |
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CN |
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101409301 |
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Jun 2013 |
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CN |
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102703880 |
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Jan 2014 |
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CN |
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2004176081 |
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Jun 2004 |
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JP |
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10-2016-0143532 |
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Dec 2016 |
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KR |
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2013/169266 |
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Nov 2013 |
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WO |
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Other References
Amusan et al; "Ag Films Grown by Remote Plasma Enhanced Atomic
Layer Deposition on Different Substrates," J. Vac. Sci. Technol. A
34(1), 01A126(2016). cited by applicant .
Hennessy et al; "Atomic Layer Deposition of Magnesium Fluoride via
bis (Ethylcyclopentadienyl)Magnesium and Anhydrous Hydrogen
Fluoride;" J. Vac. Sci. Technol. A 33(1), 01A125(2015). cited by
applicant .
Hennessy et al; "Ultraviolet Optical Properties of Aluminum
Fluoride Thin Films Deposited by Atomic Layer Deposition," J. Vac.
Sci. Technol. A 34, 01A120 (2016). cited by applicant .
Lee et al; "Characterization of Ultra-Thin HfO2 Gate Oxide Prepared
by Using Atomic Layer Deposition"; J. Kor. Phy Soc. V 42 No. 2
2003, 272. cited by applicant .
Lee et al; "Study on the Characteristics of Aluminum Thin Films
Prepared by Atomic Layer Dpeosition," J. Vac. Sci. Technol. A
20(6), 1986(2002). cited by applicant .
Pfeiffer et al; "Atomic Layer Deposition for Antireflection
Coatings Using SiO2 as Low-Refractive Index Material," Proc of SPIE
vol. 9627; 96270Q-1-96270Q-7 (2015). cited by applicant .
Poodt et al; "Spatial Atomic Layer Deposition: A Route Towards
Further Industrialization of Atomic Layer Deposition," J. Vac. Sci.
Technol. A 30(1), 010802-1(2012). cited by applicant .
Profijt et al; "Plasma-Assisted Atomic Layer Deposition: Basics,
Opportunities, and Challenges," J. Vac. Sci. Technol. A 29(5),
050801(2011). cited by applicant .
Wang et al; "Optical Coatings With Ultralow Refractive Index SiO2
Films," SPIE 7504, 75040F (2009). cited by applicant .
Bonvalot et al. "Combined spectroscopic ellipsometry and attenuated
total reflection analyses of Al2O3/HfO2 nanolaminates", Thin Solid
Films, 518(18) 2010, pp. 5057-5058. cited by applicant .
Franke et al. "estimation of the composition of
coelectron-beam-evaporated thin-mixture films by making use of the
Wiener bounds", Applied Optics, 54(9) 2015, pp. 2362-2370. cited by
applicant .
International Search Report and Written Opinion of the European
Searching Authority; PCT/US2019/031717 dated Aug. 12, 2019; 12 pgs.
cited by applicant .
Marszalek et al. "Optical properties of the Al2O3/SiO2 and
Al2O3/HfO2/SiO2 antireflective coatings", Materials
Science--Poland, 31(1) 2014, pp. 80-87. cited by applicant .
Stenzel et al. "Mixed oxide coatings for optics", Applied Optics,
50(9) 2011, pp. C69-C74. cited by applicant .
Pfeiffer, Kristin et al., "Comparative study of ALD SiO2 thin films
for optical applications," Optical Materials Express, vol. 6, pp.
660-670, Jan. 27, 2016, https://doi.or/10.1364/OME.6.000660. cited
by applicant .
Pfeiffer, Kristin et al., "Antireflection Coatings for Strongly
Curved Glass Lenses by Atomic Layer Deposition," Coatings 7(8),
118, Aug. 9, 2017, https://doi.org/10.3390/coatings7080118. cited
by applicant.
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Primary Examiner: Lei; Jie
Attorney, Agent or Firm: Bray; Kevin L.
Parent Case Text
This application claims the benefit of priority to U.S. Provisional
Application Ser. No. 62/670,187 filed on May 11, 2018, the content
of which is relied upon and incorporated herein by reference in its
entirety.
Claims
What is claimed is:
1. An optical element, comprising: an optically transparent lens
defining a curved surface comprising a steepness given by an R/# of
from about 0.5 to about 1.0, wherein the R/# value is calculated as
a radius of curvature divided by a clear aperture of the optically
transparent lens; and a film positioned on the curved surface, the
film comprising: an index layer; and a composite layer positioned
on the curved surface having a refractive index greater than the
index layer, the composite layer comprising HfO.sub.2 and
Al.sub.2O.sub.3, the HfO.sub.2 segregated into a first plurality of
layers having a thickness from 3 nm to 8 nm, the Al.sub.2O.sub.3
segregated into a second plurality of layers, wherein the composite
layer comprises a mole fraction X of HfO.sub.2, wherein X is from
0.70 to 0.90 and a mole fraction of Al.sub.2O.sub.3 in the
composite layer is 1-X and further wherein the optical element
exhibits a variance in reflectance between S-polarization and
P-polarization of from about 0% to about 0.4% over an angle of
incidence of from about 0.degree. to about 45.degree. to a central
axis of the curved surface at a wavelength of 266 nm as measured by
spectroscopic ellipsometry.
2. The optical element of claim 1, wherein the mole fraction X of
HfO.sub.2 is from about 0.75 to about 0.85.
3. The optical element of claim 1, wherein the first plurality of
layers alternate with the second plurality of layers.
4. The optical element of claim 3, wherein each layer of the first
plurality of layers is amorphous and each layer of the second
plurality of layers is amorphous.
5. The optical element of claim 3, wherein the composite layer has
a thickness, the thickness comprising about 60% of the first
plurality of layers and about 40% of the second plurality of
layers.
6. The optical element of claim 1, wherein the index layer
comprises SiO.sub.2.
7. The optical element of claim 1, wherein the composite layer has
a thickness of from about 30 nm to about 80 nm.
8. The optical element of claim 7, wherein the composite layer has
a thickness of from about 40 nm to about 70 nm.
9. The optical element of claim 1, wherein the index layer has a
thickness of from about 1 nm to about 60 nm.
10. The optical element of claim 9, wherein the index layer has a
thickness of from about 1 nm to about 30 nm.
11. The optical element of claim 1, wherein the optical element
exhibits a variance in reflectance between S-polarization and
P-polarization of from about 0% to about 0.2% over an angle of
incidence from about 0.degree. to about 45.degree. to the central
axis of the curved surface at a wavelength of 266 nm as measured by
spectroscopic ellipsometry.
12. The optical element of claim 1, wherein the composite layer is
amorphous.
Description
FIELD OF THE DISCLOSURE
The present disclosure generally relates to optical elements, and
more specifically, to curved optical elements including films.
BACKGROUND
High numerical aperture (NA) lenses for optical systems may require
many elements, some of which can have very steep surface
curvatures. Steep surfaces create challenges for high-performance
coatings over a wide angle range and/or a broad spectral bandwidth
as the application of the films to curved surfaces may produce
non-uniform thickness films and the like. Conventional films on
lenses may be produced via physical vapor deposition (PVD) which is
a line-of-sight deposition process. As coating material from the
PVD process arrives at very large angles relative to the lens
surface, the coating may exhibit thickness and mechanical
properties which may be substantially different towards the edge
compared to the center of the lens surface. The low coating
uniformity leads to high spectral reflectance and polarization
split at the edge of the lens. Several technical approaches have
been explored to address the issue, such as tilting and masking.
Both tilting and masking approaches can improve some coating
uniformity on steep surfaces, but reduces coating packing density
towards the center, leading to an increase scatter loss at the
center. Accordingly, new optical films and methods of making them
may be advantageous.
SUMMARY OF THE DISCLOSURE
According to at least one feature of the present disclosure, an
optical element including an optically transparent lens which
defines a curved surface having a steepness given by an R/# of from
about 0.5 to about 1.0. A film is positioned on the curved surface.
The film includes an index layer. A composite layer is positioned
on the curved surface having a refractive index greater than the
index layer. The composite layer includes HfO.sub.2 and
Al.sub.2O.sub.3. The composite layer has a mole fraction X of
HfO.sub.2, wherein X is from about 0.05 to about 0.95 and a mole
fraction of Al.sub.2O.sub.3 in the composite layer is 1-X.
According to another feature of the present disclosure, an optical
element includes a lens defining a curved surface. A film is
positioned on the curved surface. The film includes a laminate
layer positioned on the curved surface. The laminate layer having a
plurality of first layers including HfO.sub.2 and a plurality of
second layers includes Al.sub.2O.sub.3. An index layer includes
SiO.sub.2. The film has a variation in reflectance of from about 0%
to about 4% over a wavelength band of from about 220 nm to about
500 nm as measured across the lens and between about a 0 clear
aperture value and a 0.96 clear aperture value as measured by
reflective spectral microscopy.
According to another feature of the present disclosure, a method of
forming a film of an optical element, comprises the steps of:
positioning a substantially transparent lens in a reactor chamber,
wherein the lens defines a curved surface; exposing the lens to a
first precursor comprising at least one of Al and Hf such that the
first precursor is deposited on the curved surface of the lens;
exposing the first precursor on the curved surface to a first
oxidizer such that the first precursor present on the curved
surface of the lens reacts with the first oxidizer to form a high
refractive index layer of the film; exposing the high refractive
index layer to a second precursor such that the second precursor is
deposited on the high refractive index layer; and exposing the
second precursor on the high refractive index layer to a second
oxidizer such that the second precursor present on the high
refractive index layer reacts with the second oxidizer to form a
low refractive index layer of the film.
These and other features, advantages, and objects of the present
disclosure will be further understood and appreciated by those
skilled in the art by reference to the following specification,
claims, and appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The following is a description of the figures in the accompanying
drawings. The figures are not necessarily to scale, and certain
features and certain views of the figures may be shown exaggerated
in scale or in schematic in the interest of clarity and
conciseness.
In the drawings:
FIG. 1 is a schematic view of an optical element, according to at
least one example;
FIG. 2A is an enhanced view taken at section IIA of FIG. 1,
according to at least one example;
FIG. 2B is an enhanced view taken at section IIB of FIG. 1,
according to at least one example;
FIG. 3 is a flowchart of an exemplary method of forming the optical
element, according to at least one example;
FIG. 4 is a plot of index and extinction coefficient of an atomic
layer deposition coating Al.sub.2O.sub.3 and a physical vapor
deposition coating of Al.sub.2O.sub.3;
FIG. 5 is a plot of measured and calculated reflectance and
transmittance vs. wavelength;
FIG. 6A is a micrograph of a film coating on a lens at an apex of
the lens;
FIG. 6B is a micrograph of a film coating on a lens at an edge of
the lens;
FIG. 7A is a plot demonstrating reflectance (%) vs. wavelength of
various points on an optical lens having a coating;
FIG. 7B is a plot demonstrating reflectance (%) vs. wavelength of
various points on an optical lens having a coating;
FIG. 8 is a measured reflectance spectral distribution taken at
various points on an optical lens having a coating; and
FIGS. 9A-9G are plots of S-polarization and P-polarization
reflectance (%) vs angle of incidence for a variety of coatings
having different compositions.
DETAILED DESCRIPTION
Additional features and advantages of the invention will be set
forth in the detailed description which follows and will be
apparent to those skilled in the art from the description, or
recognized by practicing the invention as described in the
following description, together with the claims and appended
drawings.
As used herein, the term "and/or," when used in a list of two or
more items, means that any one of the listed items can be employed
by itself, or any combination of two or more of the listed items
can be employed. For example, if a composition is described as
containing components A, B, and/or C, the composition can contain A
alone; B alone; C alone; A and B in combination; A and C in
combination; B and C in combination; or A, B, and C in
combination.
In this document, relational terms, such as first and second, top
and bottom, and the like, are used solely to distinguish one entity
or action from another entity or action, without necessarily
requiring or implying any actual such relationship or order between
such entities or actions.
It will be understood by one having ordinary skill in the art that
construction of the described disclosure, and other components, is
not limited to any specific material. Other exemplary embodiments
of the disclosure disclosed herein may be formed from a wide
variety of materials, unless described otherwise herein.
For purposes of this disclosure, the term "coupled" (in all of its
forms: couple, coupling, coupled, etc.) generally means the joining
of two components (electrical or mechanical) directly or indirectly
to one another. Such joining may be stationary in nature or movable
in nature. Such joining may be achieved with the two components
(electrical or mechanical) and any additional intermediate members
being integrally formed as a single unitary body with one another
or with the two components. Such joining may be permanent in
nature, or may be removable or releasable in nature, unless
otherwise stated.
As used herein, the term "about" means that amounts, sizes,
formulations, parameters, and other quantities and characteristics
are not and need not be exact, but may be approximate and/or larger
or smaller, as desired, reflecting tolerances, conversion factors,
rounding off, measurement error and the like, and other factors
known to those of skill in the art. When the term "about" is used
in describing a value or an end-point of a range, the disclosure
should be understood to include the specific value or end-point
referred to. Whether or not a numerical value or end-point of a
range in the specification recites "about," the numerical value or
end-point of a range is intended to include two embodiments: one
modified by "about," and one not modified by "about." It will be
further understood that the end-points of each of the ranges are
significant both in relation to the other end-point, and
independently of the other end-point.
The terms "substantial," "substantially," and variations thereof as
used herein are intended to note that a described feature is equal
or approximately equal to a value or description. For example, a
"substantially planar" surface is intended to denote a surface that
is planar or approximately planar. Moreover, "substantially" is
intended to denote that two values are equal or approximately
equal. In some embodiments, "substantially" may denote values
within about 10% of each other.
It is also important to note that the construction and arrangement
of the elements of the disclosure, as shown in the exemplary
embodiments, is illustrative only. Although only a few embodiments
of the present innovations have been described in detail in this
disclosure, those skilled in the art who review this disclosure
will readily appreciate that many modifications are possible (e.g.,
variations in sizes, dimensions, structures, shapes and proportions
of the various elements, values of parameters, mounting
arrangements, use of materials, colors, orientations, etc.) without
materially departing from the novel teachings and advantages of the
subject matter recited. For example, elements shown as integrally
formed may be constructed of multiple parts, or elements shown as
multiple parts may be integrally formed, the operation of the
interfaces may be reversed or otherwise varied, the length or width
of the structures, and/or members, or connectors, or other elements
of the system, may be varied, and the nature or number of
adjustment positions provided between the elements may be varied.
It should be noted that the elements and/or assemblies of the
system may be constructed from any of a wide variety of materials
that provide sufficient strength or durability, in any of a wide
variety of colors, textures, and combinations. Accordingly, all
such modifications are intended to be included within the scope of
the present innovations. Other substitutions, modifications,
changes, and omissions may be made in the design, operating
conditions, and arrangement of the desired and other exemplary
embodiments without departing from the spirit of the present
innovations.
Referring now to FIG. 1, an optical element 10 includes a lens 14
and a film 18. As will be explained in detail below, the film 18
may be a multilayered structure which may provide one or more
properties to the lens 14 such as mechanical properties (e.g.,
scratch resistance) and/or optical properties (e.g.,
anti-reflection and color neutrality).
The lens 14 may include a glass, a glass-ceramic, a ceramic
material and/or combinations thereof. Exemplary glass-based
examples of the lens 14 may include soda lime glass, alkali
aluminosilicate glass, alkali containing borosilicate glass and/or
alkali aluminoborosilicate glass. For purposes of this disclosure,
the term "glass-based" may mean a glass, a glass-ceramic and/or a
ceramic material. According to various examples, the lens 14 may be
a glass-based substrate. In glass-based examples of the lens 14,
the lens 14 may be strengthened (e.g., alkali exchanged) or strong
(e.g., polished to remove defects). The lens 14 may be
substantially clear, transparent and/or free from light scattering.
For example, the lens 14 may have a transmittance of from about 50%
to about 100% at one or more wavelengths or wavelength bands over a
wavelength range of from about 180 nm to about 700 nm. In
glass-based examples of the lens 14, the lens 14 may have a
refractive index in the range from about 1.45 to about 1.55 at a
wavelength of about 266 nm. Further, the lens 14 of the optical
element 10 may include sapphire and/or polymeric materials.
Examples of suitable polymers include, without limitation:
thermoplastics including polystyrene (PS) (including styrene
copolymers and blends), polycarbonate (PC) (including copolymers
and blends), polyesters (including copolymers and blends, including
polyethyleneterephthalate and polyethyleneterephthalate
copolymers), polyolefins (PO) and cyclicpolyolefins (cyclic-PO),
polyvinylchloride (PVC), acrylic polymers including polymethyl
methacrylate (PMMA) (including copolymers and blends),
thermoplastic urethanes (TPU), polyetherimide (PEI) and blends of
these polymers with each other. Other exemplary polymers include
epoxy, styrenic, phenolic, melamine, and silicone resins.
The lens 14 may define one or more curved surfaces 22. The curved
surfaces 22 aid in defining the lens 14 to have a generally curved
shape. The curved surfaces 22 may form the lens 14 to have a
generally biconvex, plano-convex, positive meniscus, negative
meniscus, plano-concave, biconcave and/or combinations thereof. The
curved surface 22 may have a steepness, or "speed," which is
expressed as an R/# value. The R/# value may be calculated as a
radius of curvature (R) divided by the clear aperture of the lens
14. For purposes of this disclosure, the radius of curvature may be
defined as the distance between a vertex of the lens 14 and the
center of curvature. For purposes of this disclosure, the clear
aperture is defined as the diameter or size of the lens 14 through
which light may pass. Clear aperture may be expressed herein as a
fraction or decimal which indicates the distance from the center
(e.g., 0.0 ca) of the clear aperture to the edge (1.0 ca) of the
clear aperture. For example, halfway between the center of the
clear aperture and the edge of the clear aperture is 0.5 ca.
The R/# of the curved surface 22 may be from about 0.5 to about
1.0, or from about 0.6 to about 1.0, or from about 0.7 to about
1.0, or from about 0.8 to about 1.0, or from about 0.9 to about
1.0. For example, the R/# value may be about 0.5, about 0.55, about
0.6, about 0.65, about 0.7, about 0.75, about 0.8, about 0.85,
about 0.9, about 0.95, about 0.99, or any and all values and ranges
therebetween. According to various examples, the curved surface 22
may have an R/# value of about 0.5 or greater. It will be
understood that it is contemplated that one or more of the curved
surfaces 22 of the lens 14 may have an R/# value of greater than 1
(e.g., 2 or greater, 5 or greater, 10 or greater, or 100 or
greater) without departing from the teachings provided herein.
Still referring to FIG. 1, the film 18 is depicted as positioned
directly on the curved surface 22 of the lens 14, but it will be
understood that one or more layers, coatings and/or films may be
positioned between the film 18 and the lens 14. For example, a
crack mitigation layer, an adhesion layer, an electrically
conductive layer, an electrically insulating layer, an optical
layer, an anti-reflection layer, a protective layer, a
scratch-resistant layer, a high hardness layer, other types of
layers and/or combinations thereof may be positioned between the
film 18 and the lens 14. Further, the film 18 may be positioned on
more than one surface of the lens 14. For example, the film 18 may
be positioned across multiple curved surfaces 22 and/or extend onto
flat surfaces of the lens 14 without departing from the teachings
provided herein.
The term "film," as applied to the film 18 and/or other films
incorporated into the optical element 10, includes one or more
layers that are formed by any known method in the art, including
discrete deposition or continuous deposition processes. Such layers
may be in direct contact with one another. The layers may be formed
from the same material or more than one different material. In one
or more alternative examples, such layers may have intervening
layers of different materials disposed therebetween. In one or more
examples, the film 18 may include one or more contiguous and
uninterrupted layers and/or one or more discontinuous and
interrupted layers (i.e., layers having different materials formed
adjacent to one another).
The film 18 may be formed using various deposition methods such as
vacuum deposition techniques, for example, chemical vapor
deposition (e.g., plasma-enhanced chemical vapor deposition,
low-pressure chemical vapor deposition, atmospheric pressure
chemical vapor deposition, and plasma-enhanced atmospheric pressure
chemical vapor deposition), physical vapor deposition (e.g.,
reactive or nonreactive sputtering or laser ablation), thermal or
e-beam evaporation and/or atomic layer deposition. One or more
layers of the optical film 18 may include nano-pores or
mixed-materials to provide specific refractive index ranges or
values.
The thickness of the film 18 may be in the range from about 0.005
.mu.m to about 0.5 .mu.m, or from about 0.01 .mu.m to about 20
.mu.m. According to other examples, the film 18 may have a
thickness in the range from about 0.01 .mu.m to about 10 from about
0.05 .mu.m to about 0.5 from about 0.01 .mu.m to about 0.15 .mu.m
or from about 0.015 .mu.m to about 0.2 .mu.m. In yet other
examples, the film 18 may have a thickness from about 100 nm to
about 200 nm. It will be understood that any and all values and
ranges between above-noted values are contemplated.
According to various examples, the thickness of the film 18, or any
layers thereof as described in greater detail below, may have a
high uniformity. For example, the thickness of the film 18 and/or
any layers thereof may have a variance in thickness of from about
.+-.0 nm to about .+-.100 nm as measured between any two points
along the film 18 and/or layer. For example, the film 18 and/or any
layers thereof may have a variance in thickness of about .+-.100 nm
or less, about .+-.90 nm or less, about .+-.80 nm or less, about
.+-.70 nm or less, about .+-.60 nm or less, about .+-.50 nm or
less, about .+-.40 nm or less, about .+-.30 nm or less, about
.+-.20 nm or less, about .+-.10 nm or less, about .+-.9 nm or less,
about .+-.8 nm or less, about .+-.7 nm or less, about .+-.6 nm or
less, about .+-.5 nm or less, about .+-.4 nm or less, about .+-.3
nm or less, about .+-.2 nm or less, about .+-.1 nm or less, about
.+-.0.5 nm or less, about .+-.0.1 nm or less or any and all values
and ranges therebetween. As will be explained in greater detail
below, the high uniformity of the film 18 may be advantageous in
ensuring consistent optical properties of the optical element 10
across various clear aperture locations.
According to various examples, the film 18 may have a low carbon
content. For example, the film 18 may have a volume, mass and/or
mole percent of carbon of from about 0.01% to about 0.5%, or from
about 0.02% to about 0.4%, or from about 0.03% to about 0.3%, or
from about 0.04% to about 0.2%, or from about 0.05% to about 0.5%.
For example, the carbon content of the film 18 may be about 0.5% or
less, about 0.45% or less, about 0.4% or less, about 0.35% or less,
about 0.3% or less, about 0.25% or less, about 0.2% or less, about
0.15% or less, about 0.1% or less, about 0.09% or less, about 0.08%
or less, about 0.07% or less, about 0.06% or less, about 0.05% or
less, about 0.04% or less, about 0.03% or less, about 0.02% or
less, about 0.01% or less or any and all values and ranges
therebetween.
Referring now to FIGS. 1, 2A and 2B, the film 18 may include one or
more index layers 30 and one or more composite layers 34. As will
be explained in greater detail below, the composite layer 34 may
include two or more layers. In such examples, the composite layer
34 may be referred to as a laminate layer. In the depicted example,
the film 18 includes three index layers 30 and three composite
layers 34, but it will be understood that the film 18 may include
one or more, two or more, four or more, five or more, or six or
more index layers 30 and/or composite layers 34. According to
various examples, the index layers 30 and the composite layers 34
are positioned in an alternating manner. In other words, the film
18 may be composed of alternating layers of the index layers 30 and
the composite layers 34. It will be understood that other
orientations of the film 18 are contemplated. For example, two or
more index layers 30 or two or more composite layers 34 may be
stacked on one another without departing from the teachings
provided herein. Further, it will be understood that although the
composite layer 34 is depicted as positioned on the curved surface
22, the index layer 30 may be the layer placed on the curved
surface 22 without departing from the teachings provided
herein.
The index layers 30 may be composed of at least one of SiO.sub.2,
GeO.sub.2, SiO, AlOxNy, AlN, SiN.sub.x, Si.sub.3N.sub.4,
SiO.sub.xN.sub.y, Si.sub.uAl.sub.vO.sub.xN.sub.y, Ta.sub.2O.sub.5,
Nb.sub.2O.sub.5, TiO.sub.2, ZrO.sub.2, Al-doped SiO.sub.2, TiN,
MgO, MgF.sub.2, BaF.sub.2, CaF.sub.2, SnO.sub.2, Y.sub.2O.sub.3,
MoO.sub.3, DyF.sub.3, YbF.sub.3, YF.sub.3, CeF.sub.3,
Sc.sub.2O.sub.3 and/or combinations thereof. According to various
examples, the index layers 30 may include at least SiO.sub.2. Pure
SiO.sub.2 may be utilized in the index layers 30 in some examples
where low reflectance of the film 18 is desired.
One or more of the index layers 30 may have a thickness of from
about 1 nm to about 100 nm, or from about 1 nm to about 90 nm, or
from about 1 nm to about 80 nm, or from about 1 nm to about 70 nm,
or from about 1 nm to about 60 nm, or from about 1 nm to about 50
nm, or from about 1 nm to about 40 nm, or from about 1 nm to about
30 nm, or from about 1 nm to about 20 nm, or from about 1 nm to
about 10 nm. For example, one or more of the index layers 30 may
have a thickness of about 1 nm or greater, about 5 nm or greater,
about 10 nm or greater, about 20 nm or greater, about 30 nm or
greater, about 40 nm or greater, about 50 nm or greater, about 60
nm or greater, about 70 nm or greater, about 80 nm or greater,
about 90 nm or greater, or about 100 nm or greater. For example, at
least one of the index layers 30 may have a thickness of about 50
nm or greater. It will be understood that each of the index layers
30 present may have a different thickness than one or more of the
other index layers 30. A total thickness of the index layers 30
(e.g., for all layers added together) may be about 5 nm or greater,
about 10 nm or greater, about 20 nm or greater, about 30 nm or
greater, about 40 nm or greater, about 50 nm or greater, about 60
nm or greater, about 70 nm or greater, about 80 nm or greater,
about 90 nm or greater, or about 100 nm or greater. According to
various examples, each of the index layers 30 has a thickness of
about 1 nm or greater. According to various examples, the index
layers 30 account for about 5% or greater, about 10% or greater,
about 20% or greater, about 30% or greater, about 40% or greater,
about 50% or greater, about 60% or greater, or about 70% or greater
of the thickness of the film 18. According to various examples, one
of index layers 30 may be substantially thicker than the rest of
the index layers 30 of the film 18.
According to various examples, the index layers 30 may have a
refractive index lower than the composite layers 34. For example,
one or more of the index layers 30 may have a refractive index of
about 1.2 or greater, about 1.25 or greater, about 1.3 or greater,
about 1.35 or greater, about 1.4 or greater, about 1.45 or greater,
about 1.5 or greater, about 1.55 or greater, about 1.6 or greater,
about 1.65 or greater, about 1.7 or greater, about 1.75 or greater,
about 1.8 or greater at a wavelength of about 266 nm. According to
various examples, each of the index layers 30 has a refractive
index of about 1.2 or greater at a wavelength of 266 nm. According
to various examples, the refractive indexes of the index and
composite layers 30, 34 may be different than one another such that
the film 18 may function as an anti-reflective film. The difference
in the refractive index of the index and composite layers 30, 34
may be about 0.01 or greater, about 0.05 or greater, about 0.1 or
greater, about 0.2 or greater, about 0.3 or greater, about 0.4 or
greater, about 0.5 or greater, about 0.6 or greater, about 0.7 or
greater, about 0.8 or greater, about 0.9 or greater, or about 1.0
or greater.
As explained above, the film 18 also includes one or more composite
layers 34. Each of the composite layers 34 may have a thickness of
from about 1 nm to about 100 nm, or from about 20 nm to about 90
nm, or from about 30 nm to about 80 nm, or from about 40 nm to
about 70 nm, or from about 50 nm to about 60 nm. For example, the
composite layers 34 may have a thickness of about 1 nm or greater,
about 5 nm or greater, about 10 nm or greater, about 20 nm or
greater, about 30 nm or greater, about 40 nm or greater, about 50
nm or greater, about 60 nm or greater, about 70 nm or greater,
about 80 nm or greater, about 90 nm or greater, or about 100 nm or
greater. For example, at least one of the composite layers 34 has a
thickness of about 50 nm or greater. It will be understood that
each of the composite layers 34 present may have a different
thickness than one or more of the other composite layers 34. A
total thickness of the composite layers 34 (e.g., for all composite
layers 34 added together) may be about 5 nm or greater, about 10 nm
or greater, about 20 nm or greater, about 30 nm or greater, about
40 nm or greater, about 50 nm or greater, about 60 nm or greater,
about 70 nm or greater, about 80 nm or greater, about 90 nm or
greater, or about 100 nm or greater. According to various examples,
the composite layers 34 account for about 5% or greater, about 10%
or greater, about 20% or greater, about 30% or greater, about 40%
or greater, about 50% or greater, about 60% or greater, or about
70% or greater of a total thickness of the film 18. According to
various examples, one of composite layers 34 may be substantially
thicker than the rest of the composite layers 34 of the film
18.
According to various examples, the composite layers 34 may have a
high refractive index, relative to the index layers 30. The
composite layers 34 may have a refractive index of about 1.7 or
greater, about 1.75 or greater, about 1.8 or greater, about 1.85 or
greater, about 1.9 or greater, about 1.95 or greater, about 2.0 or
greater, about 2.05 or greater, about 2.1 or greater, about 2.15 or
greater, about 2.2 or greater, about 2.25 or greater, about 2.3 or
greater, about 2.35 or greater, about 2.4 or greater, about 2.45 or
greater, about 2.5 or greater, or about 2.6 or greater at a
wavelength of 266 nm. According to various examples, each of the
composite layers 34 has a refractive index of about 2.0 or greater
at a wavelength of 266 nm. It will be understood that the
refractive index of each of the composite layers 34 may be
different than the other composite layers 34.
Referring now to FIG. 2A, depicted is an example of the composite
layer 34 where the constituents of the composite layer 34 are not,
or are only minimally, segregated. In one aspect, the composite
layer 34 is amorphous. In another aspect, the constituents of the
composite layer 34 form a solid solution or homogeneous
composition. Constituents of the composite layer 34 may include
SiO.sub.2, Al.sub.2O.sub.3, GeO.sub.2, SiO, AlO.sub.xN.sub.y, AlN,
SiN.sub.x, Si.sub.3N.sub.4, SiO.sub.xN.sub.y,
Si.sub.uAl.sub.vO.sub.xN.sub.y, Ta.sub.2O.sub.5, HfO.sub.2,
Nb.sub.2O.sub.5, TiO.sub.2, ZrO.sub.2, TiN, MgO, MgF.sub.2,
BaF.sub.2, CaF.sub.2, SnO.sub.2, Y.sub.2O.sub.3, MoO.sub.3,
DyF.sub.3, YbF.sub.3, YF.sub.3, CeF.sub.3 and/or combinations
thereof. The composite layer 34 may have a refractive index of
about 2.1, about 2.15, about 2.2, about 2.25, about 2.3, about
2.35, about 2.4 or any and all values and ranges therebetween.
According to various examples, the composite layer 34 may be
composed of Al.sub.2O.sub.3 and HfO.sub.2. In such examples, the
mole fraction X of HfO.sub.2 may range from about 0.001 to about 1,
or from about 0.05 to about 0.95, or from about 0.10 to about 0.90,
or from about 0.60 to about 0.90, or from about 0.70 to about 0.90,
or from about 0.75 to about 0.85, or from about 0.55 to about 0.65.
For example, the mole fraction of HfO.sub.2 of the composite layer
34 may be about 0.001 or greater, about 0.005 or greater, about
0.01 or greater, about 0.05 or greater, about 0.10 or greater,
about 0.015 or greater, about 0.20 or greater, about 0.25 or
greater, about 0.30 or greater, about 0.35 or greater, about 0.40
or greater, about 0.45 or greater, about 0.50 or greater, about
0.55 or greater, about 0.60 or greater, about 0.65 or greater,
about 0.70 or greater, about 0.75 or greater, about 0.80 or
greater, about 0.85 or greater, about 0.90 or greater, about 0.95
or greater, about 0.99 or greater or any and all values and ranges
therebetween. The mole fraction of Al.sub.2O.sub.3 may be given by
the mole fraction X of HfO.sub.2 subtracted from 1. In other words,
the Al.sub.2O.sub.3 mole fraction is given by 1-X. As such, the
Al.sub.2O.sub.3 mole fraction in the composite layer 34 may range
from about 0.001 to about 1, or from about 0.05 to about 0.95, or
from about 0.10 to about 0.90. For example, the mole fraction of
Al.sub.2O.sub.30f the composite layer 34 may be about 0.001 or
greater, about 0.005 or greater, about 0.01 or greater, about 0.05
or greater, about 0.10 or greater, about 0.15 or greater, about
0.20 or greater, about 0.25 or greater, about 0.30 or greater,
about 0.35 or greater, about 0.40 or greater, about 0.45 or
greater, about 0.50 or greater, about 0.55 or greater, about 0.60
or greater, about 0.65 or greater, about 0.70 or greater, about
0.75 or greater, about 0.80 or greater, about 0.85 or greater,
about 0.90 or greater, about 0.95 or greater, about 0.99 or greater
or any and all values and ranges therebetween. According to various
examples, one or more of the composite layers 34 are amorphous. The
composition of a composite layer 34 composed of HfO.sub.2 and
Al.sub.2O.sub.3 can be expressed as XHfO.sub.2-(1-X)Al.sub.2O.sub.3
or (HfO.sub.2).sub.X(Al.sub.2O.sub.3).sub.1-X. In one aspect, a
composite layer 34 composed of HfO.sub.2 and Al.sub.2O.sub.3 is
amorphous.
Referring now to FIG. 2B depicted is a laminate example of the
composite layers 34. In such examples, the composite layers 34 each
include a first plurality of layers 38 and a second plurality of
layers 42. It will be understood that examples of the film 18 using
both the examples of FIGS. 2A and 2B of the composite layer 34 are
contemplated. For example, one or more of the composite layers 34
may be a laminate while other composite layers may be homogeneous
or non-segregated. According to various examples, the plurality of
first and second layers 38, 42 of the composite layer 34 are
stacked in an alternating order. In the depicted example, the
composite layer 34 includes three first layers 38 and three second
layers 42, but it will be understood that the composite layer 34
may include one or more, two or more, four or more, five or more,
or six or more first layers 38 and/or second layers 42. Each of the
plurality of first layers 38 may have a thickness of from about 1
nm to about 10 nm, or from about 2 nm to about 9 nm, or from about
3 nm to about 8 nm, or from about 4 nm to about 7 nm, or from about
5 nm to about 6 nm. For example each of the plurality of first
layers 38 may have a thickness about 1 nm, about 2 nm, about 3 nm,
about 4 nm, about 5 nm, about 6 nm, about 7 nm, about 8 nm, about 9
nm, about 10 nm or any and all values and ranges therebetween.
According to various examples, each of the plurality of first
layers 38 has a thickness of about 6 nm. It will be understood that
the plurality of first layers 38 may have a uniform thickness or
that one or more first layers 38 may have a different thickness
than other first layers 38. According to various examples, the
first plurality of layers 38 alternate with the second plurality of
layers 42. According to various examples, the laminate layer is
amorphous.
The plurality of first layers 38 may be composed of at least one of
SiO.sub.2, Al.sub.2O.sub.3, GeO.sub.2, SiO, AlO.sub.xN.sub.y, AlN,
SiN.sub.x, Si.sub.3N.sub.4, SiO.sub.xN.sub.y,
Si.sub.uAl.sub.vO.sub.xN.sub.y, Ta.sub.2O.sub.5, HfO.sub.2,
Nb.sub.2O.sub.5, TiO.sub.2, ZrO.sub.2, TiN, MgO, MgF.sub.2,
BaF.sub.2, CaF.sub.2, SnO.sub.2, Y.sub.2O.sub.3, MoO.sub.3,
DyF.sub.3, YbF.sub.3, YF.sub.3, CeF.sub.3, Sc.sub.2O.sub.3 and/or
combinations thereof. In one aspect, the first layer 38 is
amorphous. According to various examples, the first plurality of
layers 38 may include HfO.sub.2. According to various examples, the
first plurality of layers 38 may have a refractive index of about
2.1 or greater, about 2.15 or greater, about 2.2 or greater, about
2.25 or greater, about 2.3 or greater, about 2.35 or greater, about
2.4 or greater, about 2.45 or greater, about 2.5 or greater, about
2.55 or greater, about 2.6 or greater, about 2.65 or greater, about
2.7 or greater at a wavelength of 266 nm. According to various
examples, each of the first layers 38 has a refractive index of
about 2.3 at a wavelength of 266 nm. According to various examples,
the refractive indexes of the first and second layers 38, 42 may
have a difference of about 0.01 or greater, about 0.05 or greater,
about 0.1 or greater, about 0.2 or greater, about 0.3 or greater,
about 0.4 or greater, about 0.5 or greater, about 0.6 or greater,
about 0.7 or greater, about 0.8 or greater, about 0.9 or greater,
or about 1.0 or greater.
Each of the plurality of second layers 42 may have a thickness of
from about 1 nm to about 10 nm, or from about 2 nm to about 9 nm,
or from about 3 nm to about 8 nm, or from about 4 nm to about 7 nm,
or from about 5 nm to about 6 nm. For example each of the plurality
of second layers 42 may have a thickness about 1 nm, about 2 nm,
about 3 nm, about 4 nm, about 5 nm, about 6 nm, about 7 nm, about 8
nm, about 9 nm, about 10 nm or any and all values and ranges
therebetween. According to various examples, each of the plurality
of second layers 38 has a thickness of about 4 nm. It will be
understood that the plurality of second layers 42 may have a
uniform thickness or that one or more second layers 42 may have a
different thickness than other second layers 42.
The plurality of second layers 42 may be composed of at least one
of SiO.sub.2, Al.sub.2O.sub.3, GeO.sub.2, SiO, AlO.sub.xN.sub.y,
AlN, SiN.sub.x, Si.sub.3N.sub.4, SiO.sub.xN.sub.y,
Si.sub.uAl.sub.vO.sub.xN.sub.y, Ta.sub.2O.sub.5, HfO.sub.2,
Nb.sub.2O.sub.5, TiO.sub.2, ZrO.sub.2, TiN, MgO, MgF.sub.2,
BaF.sub.2, CaF.sub.2, SnO.sub.2, Y.sub.2O.sub.3, MoO.sub.3,
DyF.sub.3, YbF.sub.3, YF.sub.3, CeF.sub.3 and/or combinations
thereof. In one aspect, the second layer 42 is amorphous. According
to various examples, the second plurality of layers 42 may include
Al.sub.2O.sub.3. According to various examples, the second
plurality of layers 42 may have a refractive index of about 1.5 or
greater, about 1.55 or greater, about 1.6 or greater, about 1.65 or
greater, about 1.7 or greater, about 1.75 or greater, about 1.8 or
greater, about 1.85 or greater, about 1.9 or greater, about 1.95 or
greater, about 2.0 or greater, about 2.05 or greater, or about 2.1
or greater at a wavelength of 266 nm. According to various
examples, each of the second layers 42 has a refractive index of
about 1.7 at a wavelength of 266 nm.
The first plurality of layers 38 may be from about 0.1% to about
99%, or from about 10% to about 90%, or from about 20% to about
80%, or from about 30% to about 75%, or from about 50% to about
70%, or from about 52% to about 68%, or from about 54% to about
66%, or from about 56% to about 64%, or from about 58% to about 62%
of a thickness of the composite layer 34. For example, the first
plurality of layers 38 may account for about 50%, or about 51%, or
about 52%, or about 53%, or about 54%, or about 55%, or about 56%,
or about 57%, or about 58%, or about 59%, or about 60%, or about
61%, or about 62%, or about 63%, or about 64%, or about 65%, or
about 66%, or about 67%, or about 68%, or about 69% or about 70% of
the thickness of the composite layer 34. The second plurality of
layers 42 may be from about 30% to about 50%, or from about 32% to
about 48%, or from about 34% to about 46%, or from about 36% to
about 44%, or from about 38% to about 42% of a thickness of the
composite layer 34. For example, the second plurality of layers 42
may account for about 30%, or about 31%, or about 32%, or about
33%, or about 34%, or about 35%, or about 36%, or about 37%, or
about 38%, or about 39%, or about 40%, or about 41%, or about 42%,
or about 43%, or about 44%, or about 45%, or about 46%, or about
47%, or about 48%, or about 49% or about 50% of the thickness of
the composite layer 34.
Use of the first and second pluralities of layers 38, 42 may be
advantageous in decreasing a roughness of the composite layer 34
and overall the film 18. Such a feature may be advantageous in
increasing optical properties of the film 18. For examples, as
HfO.sub.2 containing examples of the first layers 38 are produced,
crystallites or grains of the HfO.sub.2 may grow, or increase in
size, as the first layer 38 is formed. Such growth of the
crystallites may result in grain coarsening which overall increases
the roughness of the composite layer 34 and the film 18. As such,
by introducing the second layers 42, which have a different
microstructure (e.g., amorphous) than the first layers 38, the
growth of the large crystals may be interrupted, disrupted, or
reset. Interrupting, or resetting, of the growth point for the
first layers 38 allows the grain size for the first layers 38 to
begin again with fine grains. Use of the second layers 42 may allow
first layers 38 formed on top of the second layer 42 to have an
average microstructural crystal size that is smaller than an
average microstructural crystal size of first layers grown without
the second layers 42. According to various examples, each layer of
the first plurality of layers 38 is amorphous and each layer of the
second plurality of layers 42 is amorphous.
"Roughness," "average surface roughness (Ra)," or like terms refer
to, on a microscopic level or below, an uneven or irregular surface
condition, such as an average root mean squared (RMS) roughness
(Rq). Ra is calculated as the roughness average of a surface's
measured microscopic peaks and valleys. Rq is calculated as the RMS
of a surface's measured microscopic peaks and valleys. When
described in terms of Rq, the roughness of the film 18, the
composite layer 34 and/or the index layer 30 may be about 20
nanometers or less, about 19 nm or less, about 18 nm or less, about
17 nm or less, about 16 nm or less, about 15 nm or less, about 14
nm or less, about 13 nm or less, about 12 nm or less, about 11 nm
or less, about 10 nm or less, about 9 nm or less, about 8 nm or
less, about 7 nm or less, about 6 nm or less, about 5 nm or less,
about 4 nm or less, about 3 nm or less, about 2 nm or less or about
1 nm or less. When described in terms of Ra, the roughness may be
about 20 nm or less, about 19 nm or less, about 18 nm or less,
about 17 nm or less, about 16 nm or less, about 15 nm or less,
about 14 nm or less, about 13 nm or less, about 12 nm or less,
about 11 nm or less, about 10 nm or less, about 9 nm or less, about
8 nm or less, about 7 nm or less, about 6 nm or less, about 5 nm or
less, about 4 nm or less, about 3 nm or less, about 2 nm or less or
about 1 nm or less.
According to various examples, the individual layer thickness of
the first and second plurality of layers 38, 42 may be much smaller
than the quarter-wave thicknesses of their constituents. For
example, the quarter-wave thickness of HfO.sub.2 (e.g., the first
layers 38) may be about 29.7 nm at a wavelength of 266 nm and the
quarter-wave thickness of Al.sub.2O.sub.3 (e.g., the second layers
42) may be about 38.4 nm at a wavelength of 266 nm. As such, the
composite layer 34 may optically be considered to be homogenous
despite the discrete layering of its constituents. Accordingly, the
refractive index and/or quarter-wave thickness of the composite
layer 34 may be a combination of the refractive index and quarter
wave thickness of the first and second layers 38, 42 based on the
relative proportions of the first and second layers 38, 42.
According to various examples, the optical element 10 including the
lens 14 and the film 18 (i.e., in either the non-segregated or
laminate examples of the composite layer 34) exhibits a variance in
reflectance between S-polarization and P-polarization of from about
0% to about 1% over an angle of incidence of from about 0.degree.
to about 45.degree. at 266 nm, or from about 0.degree. to about
58.degree. at 266 nm as measured by spectroscopic ellipsometry at a
normal angle of incidence. For example, the variance in reflectance
between S-polarization and P-polarization may be about 0.9%, about
0.8%, about 0.7%, about 0.6%, about 0.5%, about 0.4%, about 0.3%,
about 0.2%, or about 0.1% over an angle of incidence of from about
0.degree. to about 45.degree. at 266 nm, or from about 0.degree. to
about 58.degree. at 266 nm as measured by spectroscopic
ellipsometry at a normal angle of incidence. According to specific
examples, the variance in reflectance between S-polarization and
P-polarization may be about 0% to about 0.4% or from about 0% to
about 0.2% over an angle of incidence from about 0.degree. to about
45.degree. at 266 nm as measured by spectroscopic ellipsometry at a
normal angle of incidence.
The film 18 may exhibit a small variation in reflectance over a
wavelength band of from about 220 nm to about 500 nm as measured
between about a 0.0 ca clear aperture value and a 0.96 ca clear
aperture value of the lens 14 using reflective spectral microscopy.
According to various examples, the variation in reflectance may be
from about 0% to about 10%, or from about 0% to about 9%, or from
about 0% to about 8%, or from about 0% to about 7%, or from about
0% to about 6%, or from about 0% to about 5%, or from about 0% to
about 4%, or from about 0% to about 3%, or from about 0% to about
2%, or from about 0% to about 1%, or from about 0% to a out 0.1%.
For example, the variation in reflectance may be about 0%, about
0.1%, about 0.5%, about 1%, about 1.5%, about 2%, about 2.5%, about
3%, about 3.5%, about 4%, about 4.5%, about 5%, about 5.5%, about
6%, about 6.5%, about 7%, about 7.5%, about 8%, about 8.5%, about
9%, about 9.5%, about 10% or any and all values and ranges
therebetween.
Referring now to FIG. 3, depicted is an exemplary method 50 of
forming the optical element 10. The method 50 may begin with a step
54 of positioning the substantially transparent lens 14 in a
reactor chamber, wherein the lens 14 defines the curved surface 22.
According to various examples, the lens 14 may have a steepness
given by an R/# value of from about 0.5 to about 1.0. According to
various examples, the reactor may be an atomic layer deposition
reactor. In such examples, the lens 14 may be positioned within the
reactor such that one or more precursors and/or oxidizers which
enter the reactor contact the curved surface 22. Atomic layer
deposition is a thin film growth technique based on the sequential
exposure of a substrate to self-limiting surface
half-reactions.
Next, a step 58 of exposing the lens 14 to a first precursor
including at least one of Al and Hf such that the first precursor
is deposited on the curved surface 22 of the lens 14 is performed.
Although Al and Hf have been specifically called out, it will be
understood that the first precursor may include any of the
compounds noted above in connection with the composite layer 34
without departing from the teachings provided herein. The first
precursor may be exposed to the curved surface 22 for a time period
ranging from about 0.1 s to about 0.6 s, or from about 0.1 s to
about 0.5 s, or from about 0.1 s to about 0.4 s, or from about 0.1
s to about 0.3 s, or from about 0.1 s to about 0.2 s. For example,
the first precursor may be exposed to the curved surface 22 of the
lens 14 for about 0.1 s, about 0.2 s, about 0.3 s, about 0.4 s,
about 0.5 s, about 0.6 second and any and all values and ranges
therebetween. The first precursor may be composed of compounds
containing Al and/or Hf which may include organics and/or halides
of Al and Hf. For example, the first precursor may include at least
one of Trimethylaluminum, aluminum acetylacetonate,
dimethylaluminum i-propoxid, Tetrakis(diethylamino)hafnium,
Tetrakis(ethylmethylamino) hafnium, HfCl.sub.4, HfI.sub.4,
HfClxH.sub.1-x, HfCl.sub.xI.sub.1-x, HFBr.sub.4, other Al and/or Hf
containing compounds and/or combinations thereof. Once the first
precursor has been exposed to the curved surface 22 for the
predetermined time, the reactor may be purged for about 0.5 s,
about 1 s, about 1.5 s, about 2 s, about 2.5 s, about 3 s, about
3.5 s, about 4 s or for about 5 s or greater. It will be understood
that the first precursor may be used to form both the
non-segregated and laminate examples of the composite layer 34. For
example, the first precursor may include both Al and Hf containing
compounds to form the non-segregated composite layer 34. In another
example, the first precursor may include only one of Al or Hf to
form either of the first or second plurality of layers 38, 42.
According to various examples, the first precursor includes Hf and
a halide.
Next, a first oxidizer may be introduced to the reactor in a step
62 of exposing the first precursor on the curved surface 22 to the
first oxidizer such that the first precursor present on the curved
surface 22 of the lens reacts with the first oxidizer to form a
high refractive index layer of the film 18 is performed. According
to various examples, the high index layer may be either of the
first or second plurality of layers 38, 42 or the non-segregated
composite layer 34. The first oxidizer may include water vapor,
ozone, other materials which may oxidize the first precursor and/or
combinations thereof. The first oxidizer may be exposed to the
first precursor for a time period ranging from about 0.1 s to about
0.6 s, or from about 0.1 s to about 0.5 s, or from about 0.1 s to
about 0.4 s, or from about 0.1 s to about 0.3 s, or from about 0.1
s to about 0.2 s. For example, the first oxidizer may be exposed to
the first precursor for about 0.1 s, about 0.2 s, about 0.3 s,
about 0.4 s, about 0.5 s, about 0.6 second and any and all values
and ranges therebetween. It will be understood that steps 58 and 62
may be repeated until a desired thickness (e.g., of the composite
layer 34, the first layers 38 and/or second layers 42) is
reached.
Next, a step 66 of exposing the high refractive index layer to a
second precursor such that the second precursor is deposited on the
high refractive index layer is performed. The second precursor may
be exposed to the high refractive index layer for a time period
ranging from about 0.1 s to about 0.6 s, or from about 0.1 s to
about 0.5 s, or from about 0.1 s to about 0.4 s, or from about 0.1
s to about 0.3 s, or from about 0.1 s to about 0.1 s to about 0.2
s. For example, the second precursor may be exposed to the curved
surface 22 of the lens 14 for about 0.1 s, about 0.2 s, about 0.3
s, about 0.4 s, about 0.5 s, about 0.6 second and any and all
values and ranges therebetween. The second precursor may include
tris(dimethylamino)silane, bis(diethylamino)silane,
N-(diethylaminosilyl)-N-ethylethanamine, other silicon-containing
compounds, other precursors of low index materials and/or
combinations thereof. Once the second precursor has been exposed to
the high refractive index layer for the predetermined time, the
reactor may be purged for about 0.5 s, about 1 s, about 1.5 s,
about 2 s, about 2.5 s, about 3 s about 3.5 s, about 4 s or for
about 5 s or greater.
Next, a step 70 of exposing the second precursor on the high
refractive index layer to a second oxidizer such that the second
precursor present on the high refractive index layer reacts with
the second oxidizer to form a low refractive index layer of the
film 18 is performed. According to various examples, the low
refractive index layer may be the index layer 30. The second
oxidizer may include water vapor, ozone, other materials which may
oxidize the second precursor and/or combinations thereof. The
second oxidizer may be exposed to the second precursor for a time
period ranging from about 0.1 s to about 0.6 s, or from about 0.1 s
to about 0.5 s, or from about 0.1 s to about 0.4 s, or from about
0.1 s to about 0.3 s, or from about 0.1 s to about 0.1 s to about
0.2 s. For example, the second oxidizer may be exposed to the
second precursor for about 0.1 s, about 0.2 s, about 0.3 s, about
0.4 s, about 0.5 s, about 0.6 second and any and all values and
ranges therebetween.
According to various examples, steps 54-70 may be performed at an
elevated temperature. For example, steps 54-70 may be performed at
a temperature of from about 20.degree. C. to about 400.degree. C.,
or from about 100.degree. C. to about 400.degree. C., or from about
200.degree. C. to about 300.degree. C. For example, steps 54-70 may
be performed at a temperature of about 20.degree. C., about
30.degree. C., about 40.degree. C., about 50.degree. C., about
60.degree. C., about 70.degree. C., about 80.degree. C., about
90.degree. C., about 100.degree. C., about 150.degree. C., about
200.degree. C., about 250.degree. C., about 300.degree. C., about
350.degree. C., about 400.degree. C. or any and all ranges and
values therebetween. It will be understood that all the values and
ranges disclosed above may be the temperature of the lens 14, and
layers formed on the lens 14 and/or the temperature at which the
first and/or second precursors and/or oxidizers are introduced to
the reactor. For example, the method 50 may include a step of
heating the substantially transparent lens 14 to a temperature of
from about 50.degree. C. to about 350.degree. C.
It will be understood that although the steps of the method 50 were
described in a particular order, the method 50 may include
additional steps, omit steps, be repeated or performed in any order
where applicable without departing from the teachings provided
herein.
Use of the present disclosure may offer a variety of advantages.
First, as the composite layer 34 includes the first plurality of
layers 38 and the second plurality of layers 42, the roughness of
the overall film 18 may be reduced. As explained above, by stacking
the first and second layers 38, 42, crystallite growth may be
reduced which may decrease the roughness of the film 18. As
roughness of the film 18 may cause an increased scattering of light
incident on the film 18, reduction of the roughness of the film 18
may improve optical properties (e.g., scattering loss, reflection,
polarization control, etc.) of the film 18 and optical element 10.
Second, use of atomic layer deposition to produce the film 18 may
offer a variety of advantages. For example, use of atomic layer
deposition provides a self-limiting film growth technology which
enabling precise thickness control of various layers of the film 18
as well as the opportunity to simultaneously multiple surfaces of
lens 14 as well as the ability to coat multiple lenses 14
simultaneously. Third, the use of atomic layer deposition allows
high, or steep, curvature surfaces such as the curved surfaces 22
to be evenly coated while minimizing or eliminating conventional
masking processes. Fourth, as the atomic layer deposition process
may simplify tooling fixtures used to secure the lens 14 within the
reactor, a reduced risk of mechanical damage to the lenses 14 may
be realized as compared to conventional physical vapor deposition
processes. Fifth, as the film 18 may be formed with a relatively
low carbon impurity content, the film 18 may have a variety of
beneficial optical properties.
EXAMPLES
Provided below are a number of non-limiting examples of the present
disclosure.
Referring now to FIG. 4, provided is a plot of ellipsometry data of
a layer of Al.sub.2O.sub.3 formed via atomic layer deposition (e.g.
one example of the second plurality of layers 42) and a layer of
Al.sub.2O.sub.3 formed via physical vapor deposition. As
illustrated by FIG. 4, atomic layer deposition of Al.sub.2O.sub.3
leads to an increase in the refractive index (n) and extinction
coefficient (k) at lower wavelengths (e.g., about 175 nm to about
450 nm) as compared to physical vapor deposition examples. Such
optical properties achieved by the use of atomic layer deposition
to form layers of Al.sub.2O.sub.3 in a coating (e.g., the film 18)
may be advantageous in increasing the difference in refractive
index between layers of the coating which may be advantageous for
antireflective coatings.
Referring now to FIG. 5, provided is a plot of measured and
calculated reflectance (Rx) and transmittance (Tx) spectra on a 1
in.times.1 mm SiO.sub.2 substrate with an antireflective coating
having a layer of SiO.sub.2 and a layer of Al.sub.2O.sub.3 applied
via atomic layer deposition simultaneously on both sides of the
substrate. The thickness of the Al.sub.2O.sub.3 coatings was 40.5
nm and the SiO.sub.2 coatings had a thickness of 48.3 nm. The
Al.sub.2O.sub.3 was deposited using Trimethylaluminum (TMA) as the
metal precursor and water as the oxidant at about 200.degree. C. to
about 300.degree. C. The complete growth cycle was 0.2 s TMA,
followed by a 3 s purge, followed by 0.3 s of H.sub.2O, followed by
a 3 s purge. The growth rate was 1 .ANG./cycle. The SiO.sub.2 was
deposited using tris[dimethylamino] silane as the precursor and
ozone as the oxidizer at about 100.degree. C. to about 300.degree.
C. The measured and calculated values for the reflectance and
transmittance are for a 5.degree. angle of incidence of light on
the substrate and coating. As can be seen from FIG. 5, the atomic
layer deposition process of forming the coating allows for the
formation of Al.sub.2O.sub.3 and SiO.sub.2 layers which nearly
perfectly conform to optical models. As such, by utilizing atomic
layer deposition to form the coating, optical lenses formed
according to the present disclosure may closely match that of
predicted models.
Referring now to FIGS. 6A and 6B, provided are micrographs of a
first example (Example 1) of the present disclosure illustrating an
optical lens (e.g., the lens 14) having a coating (e.g. the film
18) disposed on a shaped surface (e.g., the curved surface 22). The
shaped surface had an R/# value of about 0.5 representing a
hemispherical lens. The optical lens had a diameter of about 4 mm
and a radius of curvature of 2 mm. In Example 1, Al.sub.2O.sub.3
was deposited on the optical lens during an atomic layer deposition
process using trimethylaluminum as a metal precursor and water as
the oxidant at a temperature of from about 200.degree. C. to about
300.degree. C. in a reactor. The growth of the coating was
performed by supplying trimethylaluminum to the reactor for about
0.2 seconds, purging the trimethylaluminum from the reactor for
about 3 seconds, supplying water vapor for about 0.3 seconds, and
purging the water vapor for about 3 seconds. The growth rate of the
coating was about 1 .ANG. per cycle. The thickness of the
Al.sub.2O.sub.3 coating was about 36 nm. FIG. 6A is a micrograph of
a peak, or apex, of a top of the optical lens at a clear aperture
value of about 0 ca and FIG. 6B is a micrograph of an edge of the
optical lens with a clear aperture value of about 0.9 ca. As can be
seen in FIGS. 6A and 6B, a thickness variation across of the
coating across the optical lens between the 0 ca value and 0.9 ca
value is less than 2% (36.33 nm vs. 36.70 nm) despite the high
curvature of the hemispherically shaped surface. The micrographs of
FIGS. 6A and 6B indicate that in addition to providing better
optical qualities, use of the atomic layer deposition process may
achieve highly uniform coatings across steeply curved surfaces
(i.e., without traditional masking steps) which may be advantageous
in ensuring consistent optical properties across the coating.
Referring now to FIGS. 7A and 7B, provided is reflectance data of a
second example (i.e., Example 2) at various points clear aperture
(ca) along an optical lens. The optical lens was an SiO.sub.2
hemispherical lens with a 2 mm radius of curvature. The optical
lens included a 109 nm thick Al.sub.2O.sub.3 coating. The
Al.sub.2O.sub.3 was deposited using Trimethylaluminum (TMA) as the
metal precursor and water as the oxidant at about 200.degree. C. to
about 300.degree. C. The complete growth cycle was 0.2 s TMA,
followed by a 3 s purge, followed by 0.3 s of H.sub.2O, followed by
a 3 s purge. The growth rate was 1 .ANG./cycle. The plots of FIGS.
7A and 7B provide percent reflectance vs. wavelength for points
along the optical lens radiating from the center to the edge (FIG.
7A) and rotated (FIG. 7B) along 90.degree. polar increments (e.g.,
r0 being north, r90 being east, r180 being south and r270 being
west) at a constant clear aperture value of 0.96 ca. FIG. 7A
indicates that there is about 2% or less variance in the
reflectance between the various clear aperture values of the film.
FIG. 7B indicates that there was essentially no asymmetry in
reflectance between 90.degree. separated points around the optical
lens at a clear aperture value of about 0.96 ca. As reflection is a
function coating uniformity, and as the reflectance across the
various points of the optical lens are substantially uniform (e.g.,
have a variance of about 2% or less), the atomic layer deposition
of the Al.sub.2O.sub.3 coating provides a uniform coating not only
with respect to clear aperture value of the optical lens, but also
rotationally (azimuthally) around the optical lens.
Referring now to FIG. 8, provided is a plot of measured reflectance
spectral distribution of a third example (i.e., Example 3) of the
present disclosure. Example 3 includes a coating having a SiO.sub.2
layer and an Al.sub.2O.sub.3 layer to form an antireflection
coating on a 4 mm diameter SiO.sub.2 hemisphere lens with a 2 mm
radius of curvature. The thickness of the Al.sub.2O.sub.3 coatings
was 40.5 nm and the SiO.sub.2 coatings had a thickness of 48.3 nm.
The Al.sub.2O.sub.3 was deposited using Trimethylaluminum (TMA) as
the metal precursor and water as the oxidant at about 200.degree.
C. to about 300.degree. C. The complete growth cycle was 0.2 s TMA,
followed by a 3 s purge, followed by 0.3 s of H.sub.2O, followed by
a 3 s purge. The growth rate was 1 .ANG./cycle. The SiO.sub.2 was
deposited using tris[dimethylamino] silane as the precursor and
ozone as the oxidizer at about 100.degree. C. to about 300.degree.
C. FIG. 8 provides the reflectance of Example 3 measured at a 0.61
clear aperture (0.61 ca) value and 0.96 clear aperture (0.96 ca)
value and at various polar coordinates around Example 3 (e.g., r0
being north, r90 being east, r180 being south and r270 being west).
As reflection is a function coating uniformity, and as the
reflectance across the various points of the coating have
approximately the same minimum reflectance around 285 nm, the data
indicates a uniform and symmetrical antireflective coating across
the hemisphere lens when measured near the circumference of the
lens.
Referring now to FIGS. 9A-9G depicted are calculated plots of
optical data for six different examples consistent with the optical
element 10 of the present disclosure. Each of the examples, where
indicated by relative proportions (e.g., in mole percent) of
constituents, have nano-laminated examples of mixed layers (e.g.,
segregated examples of the composite layer 34). As explained above,
mixed layers with a plurality of layers (e.g., the first and second
layers 38, 42) with thicknesses much thinner than quarter wave
thicknesses of the composition of the layers allow the mixed layer
to optically be treated as a single layer with the optical
properties of the mixed layer being based on the relative
proportions of the layers within the mixed layer. Further, examples
of the mixed layer where its constituents are homogenous, and
non-segregated, may also exhibit optical properties based on the
relative proportions of the constituents within the mixed layer. As
such, the optical properties provided in FIGS. 9A-9G are consistent
with all examples of the optical element 10. The plots of FIGS.
9A-9G are provided as percent reflectance over an angle of
incidence of from about 0.degree. to about 45.degree. at 266 nm as
measured by spectroscopic ellipsometry. As can be seen from the
plots of FIGS. 9A-9G, the variation between the S-polarization and
P-polarization is low indicating a low optical retardation. As
optical retardation is generally caused by stress in the coating,
non-uniformity of the coating, curvature of the optical lens and
other deleterious factors, the low variation in polarization
indicates a uniform and low-stress coating.
Referring now to FIG. 9A, depicted is the S-polarization and
P-polarization reflection of a six-layer antireflection coating
positioned on an SiO.sub.2 2 mm radius of curvature hemispherical
lens at 266 nm according to a fourth example (i.e., Example 4). The
antireflection coating of FIG. 9A has a layered structure, from the
lens outward, of 5.27 nm of HfO.sub.2, 11.9 nm of SiO.sub.2, 70.28
nm of HfO.sub.2, 10.96 nm of SiO.sub.2, 33.46 nm of HfO.sub.2 and
52.28 nm of SiO.sub.2.
Referring now to FIG. 9B, depicted is the S-polarization and
P-polarization reflection of a six-layer antireflection coating
positioned on an SiO.sub.2 2 mm radius of curvature hemispherical
lens at 266 nm according to a fifth example (i.e., Example 5). The
antireflection coating of FIG. 9B has a layered structure, from the
lens outward given in thicknesses, of 5.33 nm of
HfO.sub.2/Al.sub.2O.sub.3, 9.07 nm of SiO.sub.2, 70.17 nm of
HfO.sub.2/Al.sub.2O.sub.3, 12.48 nm of SiO.sub.2, 36.94 nm of
HfO.sub.2/Al.sub.2O.sub.3 and 51.32 nm of SiO.sub.2. The relative
molar proportions of HfO.sub.2 to Al.sub.2O.sub.3 for FIG. 9B are
90% HfO.sub.2 and 10% Al.sub.2O.sub.3.
Referring now to FIG. 9C, depicted is the S-polarization and
P-polarization reflection of a six-layer antireflection coating
positioned on an SiO.sub.2 2 mm radius of curvature hemispherical
lens at 266 nm according to a sixth example (i.e., Example 6). The
antireflection coating of FIG. 9C has a layered structure, from the
lens outward given in thicknesses, of 6.33 nm of
HfO.sub.2/Al.sub.2O.sub.3, 9.07 nm of SiO.sub.2, 70.17 nm of
HfO.sub.2/Al.sub.2O.sub.3, 12.48 nm of SiO.sub.2, 37.94 nm of
HfO.sub.2/Al.sub.2O.sub.3 and 51.32 nm of SiO.sub.2. The relative
molar proportions of HfO.sub.2 to Al.sub.2O.sub.3 for FIG. 9C are
80% HfO.sub.2 and 20% Al.sub.2O.sub.3.
Referring now to FIG. 9D, depicted is the S-polarization and
P-polarization reflection of a six-layer antireflection coating
positioned on an SiO.sub.2 2 mm radius of curvature hemispherical
lens at 266 nm according to a seventh example (i.e., Example 7).
The antireflection coating of FIG. 9D has a layered structure, from
the lens outward given in thicknesses, of 6.8 nm of
HfO.sub.2/Al.sub.2O.sub.3, 4.71 nm of SiO.sub.2, 69.9 nm of
HfO.sub.2/Al.sub.2O.sub.3, 16.41 nm of SiO.sub.2, 40.24 nm of
HfO.sub.2/Al.sub.2O.sub.3 and 50.54 nm of SiO.sub.2. The relative
molar proportions of HfO.sub.2 to Al.sub.2O.sub.3 for FIG. 9D are
70% HfO.sub.2 and 30% Al.sub.2O.sub.3.
Referring now to FIG. 9E, depicted is the S-polarization and
P-polarization reflection of a six-layer antireflection coating
positioned on an SiO.sub.2 2 mm radius of curvature hemispherical
lens at 266 nm according to an eighth example (i.e., Example 8).
The antireflection coating of FIG. 9E has a layered structure, from
the lens outward given in thicknesses, of 7.65 nm of
HfO.sub.2/Al.sub.2O.sub.3, 1.36 nm of SiO.sub.2, 69.76 nm of
HfO.sub.2/Al.sub.2O.sub.3, 20.6 nm of SiO.sub.2, 42.03 nm of
HfO.sub.2/Al.sub.2O.sub.3 and 49.61 nm of SiO.sub.2. The relative
molar proportions of HfO.sub.2 to Al.sub.2O.sub.3 for FIG. 9E are
60% HfO.sub.2 and 40% Al.sub.2O.sub.3.
Referring now to FIG. 9F, depicted is the S-polarization and
P-polarization reflection of a six-layer antireflection coating
positioned on an SiO.sub.2 2 mm radius of curvature hemispherical
lens at 266 nm according to a ninth example (i.e., Example 9). The
antireflection coating of FIG. 9F has a layered structure, from the
lens outward given in thicknesses, of 6.49 nm of
HfO.sub.2/Al.sub.2O.sub.3, 1.16 nm of SiO.sub.2, 71.98 nm of
HfO.sub.2/Al.sub.2O.sub.3, 23.02 nm of SiO.sub.2, 42.36 nm of
HfO.sub.2/Al.sub.2O.sub.3 and 49.67 nm of SiO.sub.2. The relative
molar proportions of HfO.sub.2 to Al.sub.2O.sub.3 for FIG. 9F are
50% HfO.sub.2 and 50% Al.sub.2O.sub.3.
Referring now to FIG. 9G, depicted is the S-polarization and
P-polarization reflection of a six-layer antireflection coating
positioned on an SiO.sub.2 2 mm radius of curvature hemispherical
lens at 266 nm according to a tenth example (i.e., Example 10). The
antireflection coating of FIG. 9G has a layered structure, from the
lens outward given in thicknesses, of 5.67 nm of HfO.sub.2, 1.73 nm
of SiO.sub.2, 68.66 nm of HfO.sub.2/Al.sub.2O.sub.3, 21.28 nm of
SiO.sub.2, 42.44 nm of HfO.sub.2/Al.sub.2O.sub.3 and 49.44 nm of
SiO.sub.2. The relative molar proportions of HfO.sub.2 to
Al.sub.2O.sub.3 for FIG. 9G are 40% HfO.sub.2 and 60%
Al.sub.2O.sub.3.
Table 1 provides the averaged reflectance of the examples of FIGS.
9A-9F at 266 nm. As can be seen from FIGS. 9A-9G and table 1, use
of the laminated layers of HfO.sub.2 and Al.sub.2O.sub.3 enables
control of reflected polarization split with a reduced average
reflection in addition to surface roughness reduction.
TABLE-US-00001 TABLE 1 Example Averaged Reflectance (%) Example 4
0.25 Example 5 0.21 Example 6 0.221 Example 7 0.19 Example 8 0.20
Example 9 0.19
Clause 1 of the description discloses:
An optical element, comprising:
an optically transparent lens defining a curved surface comprising
a steepness given by an R/# of from about 0.5 to about 1.0; and
a film positioned on the curved surface, the film comprising:
an index layer; and
a composite layer positioned on the curved surface having a
refractive index greater than the index layer, the composite layer
comprising HfO.sub.2 and Al.sub.2O.sub.3, wherein the composite
layer comprises a mole fraction X of HfO.sub.2, wherein X is from
about 0.05 to about 0.95 and a mole fraction of Al.sub.2O.sub.3 in
the composite layer is 1-X.
Clause 2 of the description discloses:
The optical element of clause 1, wherein the mole fraction X of
HfO.sub.2 is from about 0.55 to about 0.65.
Clause 3 of the description discloses:
The optical element of clause 1 or 2, wherein the HfO.sub.2 is
segregated into a first plurality of layers and the Al.sub.2O.sub.3
is segregated into a second plurality of layers, and wherein the
first plurality of layers alternate with the second plurality of
layers.
Clause 4 of the description discloses:
The optical element of clause 3, wherein each layer of the first
plurality of layers is amorphous and each layer of the second
plurality of layers is amorphous.
Clause 5 of the description discloses:
The optical element of clause 3 or 4, wherein the composite layer
has a thickness, the thickness comprising about 60% of the first
plurality of layers and about 40% of the second plurality of
layers.
Clause 6 of the description discloses:
The optical element of any of clauses 1-5, wherein the index layer
comprises SiO.sub.2.
Clause 7 of the description discloses:
The optical element of any of clauses 1-6, wherein the composite
layer has a thickness of from about 30 nm to about 80 nm.
Clause 8 of the description discloses:
The optical element of clause 7, wherein the composite layer has a
thickness of from about 40 nm to about 70 nm.
Clause 9 of the description discloses:
The optical element of any of clauses 1-8, wherein the index layer
has a thickness of from about 1 nm to about 60 nm.
Clause 10 of the description discloses:
The optical element of clause 9, wherein the index layer has a
thickness of from about 1 nm to about 30 nm.
Clause 11 of the description discloses:
The optical element of any of clauses 1-10, wherein the optical
element exhibits a variance in reflectance between S-polarization
and P-polarization of from about 0% to about 0.4% over an angle of
incidence of from about 0.degree. to about 45.degree. at 266 nm as
measured by spectroscopic ellipsometry.
Clause 12 of the description discloses:
The optical element of clause 11, wherein the optical element
exhibits a variance in reflectance between S-polarization and
P-polarization of from about 0% to about 0.2% over an angle of
incidence from about 0.degree. to about 45.degree. at 266 nm as
measured by spectroscopic ellipsometry.
Clause 13 of the description discloses:
The optical element of any of clauses 1-12, wherein the composite
layer is amorphous.
Clause 14 of the description discloses:
An optical element, comprising:
a lens defining a curved surface; and
a film positioned on the curved surface, the film comprising:
a laminate layer positioned on the curved surface, the laminate
layer comprising a plurality of first layers comprising HfO.sub.2
and a plurality of second layers comprising Al.sub.2O.sub.3; and an
index layer comprising SiO.sub.2, wherein the film has a variation
in reflectance of from about 0% to about 4% over a wavelength band
of from about 220 nm to about 500 nm as measured across the lens
and between about a 0 clear aperture value and a 0.96 clear
aperture value as measured by reflective spectral microscopy.
Clause 15 of the description discloses:
The optical element of clause 14, wherein the film has a variation
in reflectance of from about 0% to about 2% over a wavelength band
of from about 220 nm to about 500 nm as measured across the lens
and between about a 0 clear aperture value and a 0.96 clear
aperture value as measured by reflective spectral microscopy.
Clause 16 of the description discloses:
The optical element of clause 14 or 15, wherein the plurality of
first layers have a refractive index of about 2.3 at 266 nm.
Clause 17 of the description discloses:
The optical element of any of clauses 14-16, wherein the plurality
of second layers have a refractive index of about 1.7 at 266
nm.
Clause 18 of the description discloses:
The optical element of any of clauses 14-17, wherein the plurality
of first and second layers of the laminate layer are stacked in an
alternating order.
Clause 19 of the description discloses:
The optical element of any of clauses 14-18, wherein the first
plurality of layers comprise about 60% of the thickness of the
laminate layer and the plurality of second layers comprise about
40% of the thickness of the laminate layer.
Clause 20 of the description discloses:
The optical element of any of clauses 14-19, wherein the laminate
layer is amorphous.
Clause 21 of the description discloses:
A method of forming a film of an optical element, comprising the
step of:
positioning a substantially transparent lens in a reactor chamber,
wherein the lens defines a curved surface;
exposing the lens to a first precursor comprising at least one of
Al and Hf such that the first precursor is deposited on the curved
surface of the lens;
exposing the first precursor on the curved surface to a first
oxidizer such that the first precursor present on the curved
surface of the lens reacts with the first oxidizer to form a high
refractive index layer of the film;
exposing the high refractive index layer to a second precursor such
that the second precursor is deposited on the high refractive index
layer; and
exposing the second precursor on the high refractive index layer to
a second oxidizer such that the second precursor present on the
high refractive index layer reacts with the second oxidizer to form
a low refractive index layer of the film.
Clause 22 of the description discloses:
The method of clause 21, further comprising the step of:
heating the substantially transparent lens to a temperature of from
about 50.degree. C. to about 350.degree. C.
Clause 23 of the description discloses:
The method of clause 21 or 22, wherein the step of exposing the
first precursor on the curved surface to a first oxidizer further
comprises the step:
exposing the first precursor on the curved surface to water
vapor.
Clause 24 of the description discloses:
The method of any of clauses 21-23, wherein the step of positioning
the substantially transparent lens in the reactor chamber further
comprises positioning the substantially transparent lens in the
reactor chamber comprising a Steepness given by an R/# of from
about 0.5 to about 1.0.
Clause 25 of the description discloses:
The method of any of clauses 21-24, wherein the first precursor
comprises Hf and a halide.
Modifications of the disclosure will occur to those skilled in the
art and to those who make or use the disclosure. Therefore, it is
understood that the embodiments shown in the drawings and described
above are merely for illustrative purposes and not intended to
limit the scope of the disclosure, which is defined by the
following claims, as interpreted according to the principles of
patent law, including the doctrine of equivalents.
It will be understood by one having ordinary skill in the art that
construction of the described disclosure, and other components, is
not limited to any specific material. Other exemplary embodiments
of the disclosure disclosed herein may be formed from a wide
variety of materials, unless described otherwise herein.
It will be understood that any described processes, or steps within
described processes, may be combined with other disclosed processes
or steps to form structures within the scope of the present
disclosure. The exemplary structures and processes disclosed herein
are for illustrative purposes and are not to be construed as
limiting.
It is also to be understood that variations and modifications can
be made on the aforementioned structures and methods without
departing from the concepts of the present disclosure, and,
further, it is to be understood that such concepts are intended to
be covered by the following claims, unless these claims, by their
language, expressly state otherwise. Further, the claims, as set
forth below,
* * * * *
References